Emmert's law
Emmert's Law states that objects that generate retinal images of the same size will look different in physical size if they appear to be located at different distances. Specifically, the perceived size of an object increases as its perceived distance from the observer increases. This makes intuitive sense: an object of constant size will project progressively smaller retinal images as its distance from the observer increases. Similarly, if the retinal images of two different objects at different distances are the same, the physical size of the object that's farther away must be larger than the one that is closer. An easy way to experience this size/distance dependency is by viewing afterimages (which you can achieve by staring at a figure for a prolonged period of time). When we view an afterimage on a distant surface we perceive it as bigger than if we view it on a closer surface, because our brain interprets the image on the distant surface as being farther away. See also *Visual perception *Optical illusion References *Ariotti, P. (1973). On the apparent size of projected after-image: Emmert's or Castelli's law? A case of 242 years anticipation: Journal of the History of the Behavioral Sciences Vol 9(1) Jan 1973, 18-28. *Bonnet, C., & Pouthas, V. (1972). Apparent size and duration of a movement after-effect: The Quarterly Journal of Experimental Psychology Vol 24(3) Aug 1972, 275-281. *Bross, M. (2000). Emmert's law in the dark: Active and passive proprioceptive effects on positive visual afterimages: Perception Vol 29(11) 2000, 1385-1391. *Campbell, D. T. (1966). Schopenhauer, Seguin, Lubinoff, and Zehender as anticipators of Emmert's law: With comments on the uses of eponymy: Journal of the History of the Behavioral Sciences 2(1) 1966, 58-63. *Dickson, D. R. (2001). Motor activity as a determinant of the visual percept. Dissertation Abstracts International: Section B: The Sciences and Engineering. *Dwyer, J., Ashton, R., & Broerse, J. (1990). Emmert's law in the Ames room: Perception Vol 19(1) 1990, 35-41. *Dyer, F. N. (1969). The effects of the apparent size of afterimages in studies of Emmert's law: Dissertation Abstracts International. *Dyer, F. N., & Allen, T. M. (1968). Effects of the apparent size of afterimages in studies of Emmert's law: Proceedings of the Annual Convention of the American Psychological Association 3 1968, 101-102. *Fisher, G. H. (1968). Illusions and Size-Constancy: American Journal of Psychology 81(1) 1968, 2-20. *Fulgosi, A., & Fulgosi, L. (1970). The boundaries of entoptic space and Emmert's law: Acta Psychologica, Amsterdam Vol 34(4) Dec 1970, 516-520. *Furedy, J. J., & Stanley, G. (1970). The apparent size of "projected" afterimages under conditions where size-constancy holds: Perception & Psychophysics 7(3) 1970, 165-168. *Furedy, J. J., & Stanley, G. (1971). More data and arguments for partial failure of Emmert's Law under conditions of size constancy and veridical distance perception: Rejoinder to teghtsoonian's comments: Perception & Psychophysics Vol 10(2) Aug 1971, 99-100. *Gogel, W. C. (1965). Equidistance tendency and its consequences: Psychological Bulletin Vol 64(3) Sep 1965, 153-163. *Imamura, M., & Nakamizo, S. (2006). An Empirical Test of Formal Equivalence between Emmert's Law and the Size-Distance Invariance Hypothesis: The Spanish Journal of Psychology Vol 9(2) Nov 2006, 295-299. *Irwin, R. J. (1969). Emmert's law as a consequence of size constancy: Perceptual and Motor Skills 28(1) 1969, 69-70. *Kammann, R. (1967). The Overestimation of Vertical Distance and Slope and Its Role in the Moon Illusion: Perception & Psychophysics 2(12-A) 1967, 585-589. *LaVoie, A. L. (1987). Emmert's law. Washington, DC: American Psychological Association. *Lockhead, G. R., & Evans, N. J. (1979). Emmert's imaginal law: Bulletin of the Psychonomic Society Vol 13(2) Feb 1979, 114-116. *Lou, L. (2007). Apparent afterimage size, Emmert's law, and oculomotor adjustment: Perception Vol 36(8) 2007, 1214-1228. *Makosky, V. P., Whittemore, L. G., & Rogers, A. M. (1987). Activities handbook for the teaching of psychology, Vol. 2. Washington, DC: American Psychological Association. *Murch, G. M. (1968). McCollough afterimages and Emmert's law: Proceedings of the Annual Convention of the American Psychological Association 3 1968, 103-104. *Murch, G. M. (1969). Size judgments of McCollough afterimages: Journal of Experimental Psychology Vol 81(1) Jul 1969, 44-48. *Oswald, I. (1957). After-images from retina and brain: The Quarterly Journal of Experimental Psychology 9 1957, 88-100. *Ruuth, E., & Andersson, A. L. (1971). Emmert's law reconsidered: A developmental study of visual afterimages: Psychological Research Bulletin Vol 11(8) 1971, 11. *Servos, P. (2006). Preservation of Emmert's Law in a Visual Form Agnosic: Neurocase Vol 12(2) Apr 2006, 122-126. *Stacey, B., & Pike, R. (1970). Apparent size, apparent depth and the Muller-Lyer illusion: Perception & Psychophysics 7(2) 1970, 125-128. *Stanley, G. (1966). The boundary of entoptic space: Psychonomic Science Vol 5(2) 1966, 45-46. *Teghtsoonian, M. (1971). A comment on "the apparent size of "projected' afterimages under conditions where size-constancy holds." Perception & Psychophysics Vol 10(2) Aug 1971, 98. *Weintraub, D. J., & Gardner, G. T. (1970). Emmert's laws: Size constancy vs. optical geometry: American Journal of Psychology 83(1) 1970, 40-54. *Weiskrantz, L. (1950). An unusual case of after-imagery following fixation of an "imaginary" visual pattern: The Quarterly Journal of Experimental Psychology 2 1950, 170-175. *Weiskrantz, L. (2002). Prime-sight and blindsight: Consciousness and Cognition: An International Journal Vol 11(4) Dec 2002, 568-581. Category:Vision Category:Optical phenomena